<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    .box{
      width: 200px;
      height: 200px;
      background-color: rgb(231, 200, 21);
      margin: 30px auto;
    }
    .box2{
      width: 200px;
      height: 200px;
      background-color: rgb(21, 231, 231);
      margin: 30px auto;
    }
    .box3{
      width: 200px;
      height: 200px;
      background-color: rgb(186, 25, 192);
      margin: 30px auto;
    }
  </style>
</head>
<body>
  <div id="app">
    <button @click="++num">{{num}}</button>
    <div class="box" v-if="num%3 === 0">11</div>
    <div class="box2" v-else-if="num%3 === 1">22</div>
    <div class="box3" v-else>33</div>
  </div>
  <script src="./vue.js"></script>
  <script>
    const vm = new Vue({
      el: '#app',
      data: {
        num: 0
      }
    })
  </script>
</body>
</html>